Distributed charge inflator system

ABSTRACT

An inflatable system includes an inflatable component and an distributed charge inflator disposed in the inflatable component. The distributed charge inflator includes a first charge for generating inflating gas and a housing body connected to the first charge. The housing body includes an initiator and a second charge that has relatively long burn time. Upon receiving a signal from a sensor, the initiator ignites the first charge and the second charge simultaneously. The first charge inflates the inflatable component and the second charge sustains the inflation of the inflatable component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Ser. No.10/458,179filed on Jun. 11, 2003, which is a continuation-in-part ofU.S. Ser. No. 10/146,933 filed on May 17, 2002, the contents of whichare herein incorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates generally to the field of gas-generatingdevices for inflatable systems, and particularly to those used ininflatable restraint systems.

2. Background of the Invention

Prior art inflatable systems typically use an initiator (such as anelectronic squib) and a booster material (such as boron potassiumnitrate) to ignite a surrounding, much larger quantity of gas-generatingpropellant material (such as sodium azide, potassium nitrate or ammoniumnitrate, and binders). The gas-generating propellant serves as theprimary means by which sufficient gas is produced to deploy theinflatable system. The initiator, the booster material, and thesurrounding gas-generating propellant are typically all confined withina metallic structure or assembly, the whole of which forms the “gasgenerator” which produces inflating gas for an inflatable component(such as an air bag in a passenger vehicle).

This gas generator assembly typically contains one or more internalchambers or baffles, as well as one or more internal sets of filters,which are designed to: (a) control the burn rate of the propellant andthe gas mass flow rate, (b) reduce the temperature of the gases producedby the burning of the gas-generating material, and (c) filter outaccelerated particles before the gases pass through vents in theassembly and into the airbag itself.

The gas generator is typically located in a position external to theinflatable component (e.g. an airbag) itself, and is attached to theinflatable component by a conduit through which the generated gases flowinto the inflatable component, causing the inflatable component todeploy.

Such prior art systems are disclosed, for example, in U.S. Pat. No.5,738,374 (a pyrotechnic gas generator for an air bag using an annularcharge of a mixture of ammonium perchlorate and sodium nitrate, with asilicone binder); U.S. Pat. No. 5,623,115 (a gas generator including apyrogen igniter enclosing a unitary grain of ignition material, with asquib located to ignite the unitary grain); U.S. Pat. No. 5,483,896 (ahousing for a pyrotechnic inflator which serves as a filter forentrapping contaminants and as a cooler by absorbing heat from thegenerated gas); U.S. Pat. No. 5,443,286 (a gas generating cartridgesurrounded by filtering and cooling screens); U.S. Pat. No. 4,200,615 (alinear igniter and pyrotechnic material extending longitudinally withinan elongated enclosure); U.S. Pat. No. 4,950,458 (a two-stage gasgenerator, in which each stage includes a combustion chamber with anigniter); and U.S. Pat. No. 4,923,212 (a lightweight pyrotechnicinflator consisting of six component parts, including mechanical parts,a filter, a propellant assembly and an initiator).

Hybrid inflators such as the inflators disclosed in U.S. Pat. No.5,670,738 (a hybrid inflator using compressed gas together with aninitiator and a pyrotechnic gas generator), U.S. Pat. No. 5,660,412 (ahybrid inflator consisting of a pressure vessel containing a main chargeof pyrotechnic material and a secondary charge of pyrotechnic material,wherein the secondary charge produces products of combustion that ignitethe main charge), U.S. Pat. No. 5,588,676 (a hybrid inflator with apyrotechnic gas generator and a gas chamber storing pressurized gas),U.S. Pat. No. 5,462,307 (a hybrid air bag inflator with a first chambercontaining compressed gas and a second chamber containing an igniter andpyrotechnic material) and U.S. Pat. No. 5,131,680 (an inflator assemblywhich includes pyrotechnic material and a container of gas underpressure) also use gas generating units that are completely separatefrom and external to the inflatable component (e.g., the air bag)itself.

U.S. Pat. No. 6,062,143, which is assigned to the assignee of thepresent application and is incorporated herein by reference, discloses adistributed charge inflator. The distributed charge inflator generallyincludes a distributed gas-generating material, that may have a fasterburning center core ignition material surrounded by supplementalpropellant, or uses a homogenous mixture of ignition material andpropellant, and also includes an initiator (e.g., an electronic squib)used to ignite the gas generating material upon a signal from aninitiating device. The fast burning gas generating material or“distributed charge” is designed to be installed within and distributedalong the interior of the undeployed inflatable component itself. It isnot necessary to contain the distributed charge inflator (DCI) withinany type of exterior housing or assembly. The distributed chargeinflator is simpler and less expensive to manufacture than the prior artsystems listed above, because it does not require the complicated seriesof chambers, baffles, or filters. Also, because distributed chargeinflator is distributed, rather than confined to a small enclosedcontainer as in the prior art systems listed above, it generates gasesand releases the generated gases with far less explosive force than inthe prior art systems. The internal distributed charge inflator systemvirtually eliminates the uneven inflations, pressure waves, and inertialeffects of gases injected into the inflatable components from externallylocated gas generators. Moreover, the distributed charge inflatorequipped inflatable restraints deploy less aggressively than existingsystems because the energy of the expanding gases is essentiallydistributed uniformly throughout the inflatable structure duringdeployment.

Further, because the distributed charge inflator is distributedinternally within the inflatable component, there is no necessity toreinforce the inflatable fabric or bladder material against pressure,heat and high velocity particulates at the point at which gases wouldhave been forcefully injected into the inflatable component from the gasgenerator external to the inflatable component. Furthermore, there is noneed for a reinforced fill tube, or other means for providing a secureconduit from the gas generator to the inflatable component.

An additional advantage is that it can be readily scaled to theparticular application. Almost every different vehicle platform ordifferent application requires a different volume of the inflating gas,or a different rate of inflation.

The distributed charge inflator is not limited to simply propagating therapid ignition of other materials, the burning of which then producesthe quantities of gas necessary to inflate a given structure. Thedistributed charge inflator system is a complete, autonomously-operatinginflation system.

Example of inflatable components which the distributed charge inflatorcan be used to inflate are described in U.S. Pat. No. 5,282,648 (bodyand head restraints); U.S. Pat. No. 5,322,322 (side impact head strikeprotection); U.S. Pat. No. 5,480,181 (side impact head strikeprotection); and U.S. Pat. No. 5,464,246 (tubular cushions), which areincorporated herein by reference, as well as automotive air bags andother inflatable products.

SUMMARY OF THE INVENTION

The present invention is an improved inflator system that can be used inconjunction with a wide variety of inflatable systems such as inflatablerestraint systems, inflatable flotation systems, or passive inflatablesafety systems.

An inflatable system of the present invention includes an inflatablecomponent and a distributed charge inflator disposed in the inflatablecomponent. The distributed charge inflator includes a housing body and adistributed charge connected to the housing body. Upon receiving asignal from a sensor, an initiator in the housing body ignites thedistributed charge, thus inflating the inflatable component.

The housing body may also include a sustainer having a longer burn timethan the distributed charge. The initiator ignites the distributedcharge and the sustainer simultaneously upon receiving the signal fromthe sensor. The distributed charge combusts over a first time intervalto inflate the inflatable component and the sustainer combusts over asecond time interval to maintain the inflation of the inflatablecomponent. Optionally, the housing body may include a booster to helpthe ignition of the distributed charge. The booster may be looselyplaced within the housing body. Alternatively, the booster may becompressed in a container that is placed around the initiator in thehousing body.

The distributed charge inflator of the present invention may be used ina side impact protection system. In one embodiment, the distributedcharge inflator includes a housing body and more than one distributedcharge having different deployment characteristics. The distributedcharge inflator is disposed in an inflatable component of the sideimpact protection system. Each of the distributed charges is disposed indifferent sections (e.g., chambers) of the inflatable component. Thedistributed charges, having different deployment characteristics,disposed in the different sections of the inflatable component may causethe different sections of the inflatable component to be inflated withdifferent deployment characteristics, such as different timing,different pressures and/or different burn rates. The distributed chargesmay assume any shape. The distributed charges do not need to beuniformly (or evenly) distributed within the sections of the inflatablecomponent.

The distributed charge inflator of the present invention may also beused in a front impact protection system. The distributed chargeinflator including a distributed charge and a housing body is disposedin an inflatable component of the front impact protection system. Thedistributed charge may assume any shape. The distributed charge does notneed to be uniformly (or evenly) distributed within the inflatablecomponent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an inflatable system according to apreferred embodiment of the present invention.

FIG. 2 is a schematic diagram of an exemplary inflatable systemaccording to a preferred embodiment of the present invention.

FIG. 2 a is a cross-sectional view of the exemplary inflatable system inFIG. 2.

FIG. 3 is a cross-sectional view of an exemplary distributed chargeinflator according to a preferred embodiment of the present invention.

FIGS. 4, 5 and 6 are schematic diagrams of exemplary implementations ofthe present invention.

FIG. 7 is a schematic diagram of an alternate inflatable system of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 shows an inflatable system according to a preferred embodiment ofthe present invention.

Inflatable system 100 includes an inflatable component 101 and adistributed charge inflator 110 disposed in inflatable component 101.Distributed charge inflator 110 includes a housing body 102 and adistributed charge 104 connected to housing body 102. Distributed charge104 may be a solid monolithic block of pyrotechnic materials formed intothe desired configuration using binders. The pyrotechnic material (withor without binders) may be enclosed by an exterior sheath, layer orcoating for environmental protection. Alternatively, the distributedcharge may include a core of ignition material and a sheath. Optionally,the distributed charge may also include a gas generating layer orcoating. Housing body 102 includes an initiator for igniting thedistributed charge. Housing body 102 may also include a sustainer thatexhibits relatively long burn time. Housing body 102 may be any type ofinflator. The housing body may be a compressed gas inflator or a hybridinflator.

Inflatable system 100 receives an electric signal from an activatoralong a wire 103, when a crash sensor or other activator determines thatthe inflatable component must be deployed. Upon receiving the electricalsignal, the initiator in the housing body ignites distributed charge104, generates inflating gas, thus deploying inflatable component 101.Simultaneously, the initiator may also ignite the sustainer in thehousing body, thus sustaining the inflation of the inflatable component.

FIG. 2 shows an exemplary inflatable system according a preferredembodiment of the present invention.

Inflatable system 200 includes an inflatable component 201 and adistributed charge inflator 210 disposed in inflatable component 201.Distributed charge inflator 210 includes a housing body 202 and adistributed charge 204 connected to housing body 202. FIG. 2A showsacross-sectional view of inflatable system 200. As shown, housing body202 includes an initiator 230 and a sustainer 205. Sustainer 205 is heldand supported by a retaining ring 220 and a spring 222 in housing body202. Spring 222 accommodates for different loads of sustainer 205 tosuit the specific application. Other elastic materials or mechanisms canbe used as alternatives to spring 222. Housing body 202 also includes anozzle screen 232 and a ferrule 234. Nozzle screen 232 retains sustainer205 in housing body 202. Ferrule 234 joins housing body 202 todistributed charge 204 by mechanically holding the distributed charge.Ferrule 234 also controls the output of the housing body.,

Initiator 230 ignites both of sustainer 205 and distributed charge 204.Combustion of distributed charge 204 generates a high volume of gaswhich inflates inflatable component 201 from stowed to deployedconditions. The distributed charge typically combusts over a relativelyshort time interval (typically between 1 and 20 ms, preferably 5 ms). Tomaintain inflation of the inflatable component, the sustainer isprovided to combust over a relatively longer interval (typically between50 to 500 ms, preferably 200 ms). The gas generated from combustion ofthe sustainer can be vented from the housing body through the ferrule.

Optionally, housing body 202 may include a booster (not shown) to helpthe ignition of the distributed charge. The booster may be looselyplaced within the housing body. Alternatively, the booster may becompressed in a container and placed in the housing body. FIG. 3 showsan exemplary embodiment of the distributed charge inflator including thebooster compressed in a container. As shown, a housing body 302 ofdistributed charge inflator 310 includes an initiator 320 and a booster333 compressed in a container 330. Container 330 may be placed aroundinitiator 320, thus forming a “micro gas generator.” The micro gasgenerator eliminates the need for a booster assembly packet that is usedwith the booster loosely placed within the housing body, thussimplifying assembly of the housing body. Further, since the booster iscompressed, the booster combusts more efficiently than the looselyplaced booster. Boron potassium nitrate (BKN03), for example, may beused as the booster.

The length of the time intervals over which the distributed charge andthe sustainer are combusted can be selected for the particularapplication. For example, the inflatable component for a side impactprotection system for a sports utility vehicle needs to become fullyinflated within 15 ms, and needs to remain inflated for at least 2.5seconds, preferably as long as 7 seconds or more so that it can protectits occupants in a rollover. Preferably, the inflatable component forfront impact protection system should become fully inflated within 30 msand should remain inflated for 100 ms.

The distributed charge in the distributed charge inflator may bemanufactured in various sizes and configurations, depending upon theinflation requirements of the system for which it is intended. These mayrange from a foil or thin film, or linear or tubular shaped charges tobroad flat sheets of distributed charge material which may be cut,trimmed, or otherwise fitted. For example, distributed charge 104 inFIG. 1 and distributed charge 204 in FIG. 2 are configured as linearcharges.

Further, the distributed charge inflator of the present invention can bedesigned so that, depending on deployment characteristics of thedistributed charges or the pattern of distribution of the distributedcharges within a given inflatable system, different sections of theinflatable component can be inflated with different deploymentcharacteristics, such as different timing, different pressures and/ordifferent burn rates.

FIGS. 4, 5 and 6 show examples of implementations of the presentinvention.

FIG. 4 shows an exemplary implementation of the distributed chargeinflator of the present invention in a side impact protection system. Asshown, the distributed charge inflator includes a housing body and morethan one linear charge (i.e., a distributed charge in linearconfiguration) connected to the housing body. The distributed chargeinflator includes housing body 402 and linear charges 403 and 404connected to housing body 402. Housing body 402 includes an initiatorfor igniting the linear charges. Housing body 402 may also include asustainer. The distributed charge inflator is disposed in inflatablecomponent 401 of the side impact protection system. The inflatablecomponent of the side impact protect system includes multiple sections(or chambers). For example, inflatable component 401 includes sections410 and 412. Each of the linear charges is disposed in each of themultiple sections of the inflatable component. Linear charge 403 isdisposed in section 410 and linear charge 404 is disposed in section 412of inflatable component 401. The linear charges may assume any shape.For example, the linear charges may be coiled, as shown in FIG. 4, orstraight or knotted. FIG. 5 illustrates linear charge 403 with differentshape. Linear charges 403 and 404 are configured to have differentdeployment characteristics so that the sections of the inflatablecomponent can be inflated with different timing, different pressuresand/or different burn rates, depending upon the inflation requirementsof the system for which it is intended. The length of the linear chargescan be selected so as to control the deployment time and the pressure ofdifferent sections of the inflatable component. The linear charges maybe formed of different materials or composition having different burnrates. The linear charges may also be in different shapes.

The initiator in housing body 402 ignites both of linear charges 403 and404 upon receiving a signal from an activator. Ignition of linear charge403 and 404 causes inflation of inflatable component 401 with sections410 and 412 inflating with different timing and/or different pressures.By providing the linear charges having different deploymentcharacteristics in the different sections of the inflatable component,the inflatable component can be inflated with the different sections ofthe inflatable component inflating with different deploymentcharacteristics, such as different timing, different pressures and/ordifferent burn rates depending upon the inflation requirements of thesystem for which it is intended. The sections of the inflatablecomponent that inflates fast, for example, can provide protection forrapid crash event, such as a primary impact, and the sections of theinflatable component that inflates slowly and has a long burn time canprovide protection for slower developing crash events, such as arollover.

The linear charge does not need to be uniformly (or evenly) distributedwithin the section of the inflatable component. Even without the linearcharge evenly distributed in the inflatable component, the distributedcharge inflator of the present invention provides advantages over theprior art systems. The distributed charge inflator of the presentinvention is still simpler and less expensive to manufacture than theprior art systems because it does not require the complicated series ofchambers. Also, because the linear charge is not confined to a smallenclosed container, it generates gases and releases the generated gaseswith far less explosive force than in the prior art systems. Further,when the linear charge is disposed within the inflatable component,there is no necessity to reinforce the inflatable fabric. Furthermore,there is no need for a reinforced fill tube, or other means forproviding a secure conduit from the gas generator to the inflatablecomponent.

FIG. 6 shows an exemplary implementation of the distributed chargeinflator of the present invention in a front impact protection system.The distributed charge inflator includes a housing body 602 and a linearcharge 603 connected to the housing body. The distributed chargeinflator is disposed in an inflatable component 601. Linear charge 603may assume any shape. In FIG. 6, for example, linear charge 602 iscoiled. The linear charge does not need to be evenly distributed withinthe inflatable component. The front impact protection system may bemounted in an instrument panel 604 of an automobile.

Illustrated in FIG. 7 is an alternate inflatable system 700substantially similar to inflatable system 100 of FIG. 1. Included insystem 700 are an inflatable component 701 and a distributed chargeinflator 710 disposed therein. Like inflator 110 of FIG. 1, distributedcharge inflator 710 may include a housing body 702 and a distributedcharge 704 connected thereto. However, initiator 730 need not bepositioned at an end of housing body 702 opposite distributed charge704, but rather may be positioned anywhere appropriate along or withinhousing body 702. Indeed, in some embodiments of the invention (anexemplary one of which is shown in FIG. 7), initiator 730 may be near oradjacent either or both of distributed charge 704 and any containerpresent in the housing so as to reduce further the interval between whenan initiating signal is received by initiator 730 via wire 703 andcharge 704 and any sustainer or booster is ignited or otherwiseinitiated. Further, as should be readily apparent to those skilled inthe relevant field, either or both of any sustainer or booster presentin the invention may comprise compressed gas housed in a container, withthe gas having an onset rate differing from (and, at least for anysustainer, typically slower than) the burn or onset rate of charge 704.

The foregoing disclosure of the preferred embodiments of the presentinvention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many variations andmodifications of the embodiments described herein will be apparent toone of ordinary skill in the art in light of the above disclosure. Thescope of the invention is to be defined only by the claims appendedhereto, and by their equivalents.

Further, in describing representative embodiments of the presentinvention, the specification may have presented the method and/orprocess of the present invention as a particular sequence of steps.However, to the extent that the method or process does not rely on theparticular order of steps set forth herein, the method or process shouldnot be limited to the particular sequence of steps described. As one ofordinary skill in the art would appreciate, other sequences of steps maybe possible. Therefore, the particular order of the steps set forth inthe specification should not be construed as limitations on the claims.In addition, the claims directed to the method and/or process of thepresent invention should not be limited to the performance of theirsteps in the order written, and one skilled in the art can readilyappreciate that the sequences may be varied and still remain within thespirit and scope of the present invention.

1-14. (canceled)
 15. An inflatable system comprising: an inflatablecomponent including a plurality of chambers, wherein the plurality ofchambers include a first chamber and a second chamber; a plurality ofcharges for generating inflating gas, wherein the plurality of chargesinclude a first charge and a second charge, the first charge is disposedin the first chamber and the second charge is disposed in the secondchamber; and a housing body including an initiator and connected to theplurality of charges, wherein the initiator ignites the plurality ofcharges and generates inflating gas which inflates the inflatablecomponent such that the first chamber and the second chamber of theinflatable component are inflated with different deploymentcharacteristics.
 16. The inflatable system of claim 15, wherein thefirst charge and the second charge have different deploymentcharacteristics.
 17. The inflatable system of claim 16, wherein thedeployment characteristics are determined by a shape, a length or acomposition of each of the first charge and the second charge.
 18. Theinflatable system of claim 15, wherein the different deploymentcharacteristics include different timing, different pressures ordifferent burn rates.
 19. The inflatable system of claim 15, wherein thefirst chamber of the inflatable component provides protection for arapid crash event and the second chamber of the inflatable componentprovides protection for slower developing crash events.
 20. Theinflatable system of claim 15, wherein the first charge and the secondcharge have a linear configuration that can assume any shape.
 21. Theinflatable system of claim 15, wherein the housing body further includesa third charge for maintaining the inflation of the inflatablecomponent.
 22. The inflatable system of claim 21, wherein the initiatorignites the first charge, the second charge and the third chargesimultaneously.
 23. The inflatable system of claim 15, wherein thehousing body further includes a fourth charge to boost the ignition ofthe plurality of charges.
 24. The inflatable system of claim 23, whereinthe fourth charge is compressed in a container and the container isplaced around the initiator. 25-28. (canceled)